Computer simulation of the effect exerted by argon matrix on the internal
rotation barriers and torsional states of methanol molecule

G.A. Pitsevich, Maksim Shundalau

Belarusian State University, Minsk, Belarus

Abstract

In the approximation B3LYP/cc-pVTZ, the geometry of a methanol molecule surrounded by eight argon atoms has been optimized. Using a fixed configuration of argon atoms, the internal rotation barriers of methyl and hydroxyl groups, the values of which are compared with that for a free molecule, have been computed. It has been found that insignificant differences in the form of the potential function as compared to a free molecule occur only on rotation of a hydroxyl group, being independent of the methyl group position with respect to the argon lattice. The torsional state energies of a methanol molecule surrounded by argon atoms have been computed taking the difference in the potential functions of the hydroxyl group rotation with respect to the lattice and internal rotation in a free molecule as a perturbing factor. According to the results of these computations, degeneracy of the E-type states is relieved with a slight increase in splitting of the ground torsional state.